The influence of conjugate natural convective heat transfer on the temperature field in a monocrystalline sapphire tape in the Stepanov method

Natural convective heat transfer in the system “monocrystalline tape – environment – walls of the growth vessel”, geometrically similar to the simplified scheme of the upper part of the heat node in the Stepanov method, is studied numerically by the finite element method in the conjugate formulation. The calculations were performed with a Prandtl number equal to 0.68 (argon), in the range of Grashof numbers 1000 ≤ Gr ≤ 25000 and with a discrete set of tape lengths in the range from 1 to 5.

Influence of the relative dimensions of the cavity on the conjugate convective heat transfer and on the shape of crystallization fronts in the method of Horizontal Directed Crystallization

The process of water crystallization in rectangular cavities is numerically studied. The liquid being studied is water having an inverse temperature dependence of the density. Calculations were carried out with a suddenly cooled vertical wall of a rectangular cavity. The initial temperature of the melt is maintained on the opposite wall. The finite element method was used to solve a system of equations for the nonstationary free convection of a melt, taking into account the dependence of the density on temperature. The heat conduction equation in the solidified substance was also solved. The problems were solved in a conjugate formulation taking into account the release of the latent heat of crystallization at the liquid-solid interface.

Numerical Simulation of Natural Convection in the Air Gap of a Vertical Flat Plat Thermal Solar Collector with Partitions Attached to Its Glazing

Heat transfer in the air gap of a vertical flat plat thermal solar collector containing partitions attached to its glazing has been studied numerically. The absorber and the glazing are kept at constant and different temperatures, while the vertical walls (insulation) were kept adiabatically. A conjugate formulation was used for mathematical formulation of the problem and a computer program based on the control volume approach and the simpler algorithm was used. The main aim of the current paper is to study numerically the effects of number of fins and their length on the air pattern and heat transfer. Experimental results showed that interesting phenomena happened, especially in the heat transfer process. It was observed that the heat transfer rate through the air gap is affected greatly and can be controlled by the number of attached fins to the glazing of the solar collector as well as the fin lengths, and the addition of partitions reduces the heat losses by convection by 60%. This study will brings good advantages for further uses, especially related to the heat transfer phenomena in the solar applications.

Synthesis and characterization of TPGS–gemcitabine prodrug micelles for pancreatic cancer therapy

Evaluation of a novel polymer-drug conjugate formulation in pancreatic cancer.

Numerical Investigation of Combustible Channel Walls Ignited by Gas Flow

A study is made of the process of ignition of reactive channel walls by a laminar flow of hot gases, including the stages of heating of a substance and of reacting in the surface layer with self-acceleration of the chemical reaction. The process is determined by the heat exchange between the gas and the wall, the strength of the heat source in the chemical-reaction zone, and the sink of heat due to conduction in the radial and axial directions. In the stage of self-heating, we can have heat sink not only deep into the wall and/or through its external boundary but into the gas flow as well. The problem has been solved in a conjugate formulation. The influence of the temperature, the velocity of the gas at the entrance to the channel, and the wall thickness on ignition characteristics has been studied.In spreading a high temperature gas flow in a channel which walls are made of reactable material there appears a problem dealing with the possibility of their ignition by the flow.

Axial Heat Conduction in the Context of Developing Flows in Microchannels

For practical microchannel applications involving convective heat transfer, the flows are usually, not only laminar, they are also simultaneously developing in nature. Moreover, flat plate substrates with microchannels engraved/ machined or etched on them are emerging as one of the most popular flow geometries. Not analyzing such situations as conjugate heat transfer problems with multi-dimensional effects, often leads to erroneous estimation of heat transfer coefficients. In this context, we report three dimensional numerical simulations of simultaneously developing internal convective flow through a square microchannel (side = 400 μm), treating the substrate thickness, flow Reynolds number and the thermal conductivity of the substrate and the fluid, in the conjugate formulation. Constant heat flux is applied at the bottom of the substrate, away from the fluid-solid interface, as in real-time situations. The parametric study reveals that depending on geometry considerations, flow parameters and thermo-physical properties of fluid-solid combination, conjugate heat transfer effects must be accounted for, to correctly estimate the local Nusselt number.